[Xen-changelog] [xen master] x86/HVM: XSETBV intercept needs to check CPL on SVM only

[patchbot@xxxxxxx]

commit e513d8f7bc3db90e66bd2ed963b3142f412b770d
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Dec 2 15:21:15 2015 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Dec 2 15:21:15 2015 +0100

    x86/HVM: XSETBV intercept needs to check CPL on SVM only
    
    VMX doesn't need a software CPL check on the XSETBV intercept, and
    SVM can do that check without resorting to hvm_get_segment_register().
    
    Clean up what is left of hvm_handle_xsetbv(), namely make it return a
    proper error code.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c     |   19 ++++++-------------
 xen/arch/x86/hvm/svm/svm.c |    9 +++++----
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index db0aeba..af3d4d7 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3153,22 +3153,15 @@ out:
 
 int hvm_handle_xsetbv(u32 index, u64 new_bv)
 {
-    struct segment_register sreg;
-    struct vcpu *curr = current;
-
-    hvm_get_segment_register(curr, x86_seg_ss, &sreg);
-    if ( sreg.attr.fields.dpl != 0 )
-        goto err;
+    int rc;
 
-    hvm_event_crX(XCR0, new_bv, curr->arch.xcr0);
+    hvm_event_crX(XCR0, new_bv, current->arch.xcr0);
 
-    if ( handle_xsetbv(index, new_bv) )
-        goto err;
+    rc = handle_xsetbv(index, new_bv);
+    if ( rc )
+        hvm_inject_hw_exception(TRAP_gp_fault, 0);
 
-    return 0;
-err:
-    hvm_inject_hw_exception(TRAP_gp_fault, 0);
-    return -1;
+    return rc;
 }
 
 int hvm_set_efer(uint64_t value)
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 200a5df..9415fb1 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -2612,10 +2612,11 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
         break;
 
     case VMEXIT_XSETBV:
-        if ( (inst_len = __get_instruction_length(current, INSTR_XSETBV))==0 )
-            break;
-        if ( hvm_handle_xsetbv(regs->ecx,
-                               (regs->rdx << 32) | regs->_eax) == 0 )
+        if ( vmcb_get_cpl(vmcb) )
+            hvm_inject_hw_exception(TRAP_gp_fault, 0);
+        else if ( (inst_len = __get_instruction_length(v, INSTR_XSETBV)) &&
+                  hvm_handle_xsetbv(regs->ecx,
+                                    (regs->rdx << 32) | regs->_eax) == 0 )
             __update_guest_eip(regs, inst_len);
         break;
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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